LG G3 Camera Laser Auto focus Explained

May 28, 2014

laser auto focus LG G3

The LG G3 is here, and it brings some new fresh technologies into the mobile photography world, and yes, I’m talking about the Laser Auto focusing system for the rear camera of the LG G3.

Laser AF System Overview

This technology is not all brand new. Sony already used this technology in the past in some of its digital cameras, like in the Sony F707, DSC-V3 and DSC-F828 and called it ‘Hologram AF’. So that laser AF technology was actually used by Sony in its Cybershot cameras around the year 2003.

In Sony cameras which utilized this “hologram” AF system, the AF system was contrast-detect based and used a laser on the subject to get an accurate distance measurement and focus correctly in low-light. The problem with this system is that it’s limited in range due to the low power of the laser (Sony used Class 1 laser, which is safe for this purpose). According to Sony, the maximum distance of effectiveness was up to 4.5 meters.

By using this method, the can process and detect the difference in contrast between the subject and the edge of the laser pattern that was draw onto the scene, and therefore get a reliable and accurate focus. The problem with that system that is was relatively slow, and therefore wasn’t the ideal AF system for professional use — but it did a fine job in consumer digital cameras.

As for today, most digital cameras use a LED or utilize the flash to light up the scene to quickly lock on the subject.

In more advanced cameras (e.g. DSLR  cameras) , the preferred method was to use phase-detect AF system that was faster than contrast-detect, and combine it with IR illumination to get an accurate focus when shooting in low-light situations.

According to nikonrumors.com website , laser AF was one the projects that Nikon cancelled. Nikon was testing a prototype camera that uses a laser beam to accurately calculate the focus distance of a subject in low-light. Nikon eventually decided (according to the rumor) a revamped phase-detection AF system. The problem with Laser AF was again its speed and the ability to use it well when on moving subjects.

LG G3 Laser Auto Focus System

So the laser AF technology is back, and now in the LG G3. The LG G3 is the first to use Laser Auto Focus. According to LG, this is the same technology that police use toe measure car’s speed.   So it would be great if LG was able to improve the AF response-time of the Laser Auto Focus system. According to LG internal tests, the response-time of the laser AF system is 0.276 seconds. This speed varies on various shooting conditions, but on paper, it’s very fast.

By utilizing this revamped laser technology, LG was able to significantly improve the Auto focusing speed.  LG demonstrated the Laser AF versus Phase Detection AF in the LG G3 launch event. Although it didn’t state which phone was used for the phase-detection AF (but it’s obviously the Samsung Galaxy S5), the laser AF did a much better job. The camera of the LG G3 was able to focus faster on the LG G3 in very dim light. The Samsung Galaxy S5 phase-detection system will focus faster in well lit conditions. Phase-detection is used in all DSLR cameras, and also in mirrorless cameras. In recent years, many digital cameras start utilizing on-sensor phase-detect points to used phase-detection AF for Live View and in video. So this phase-detection technology is preferred for faster and more accurate AF for subject tracking and in well lit environments.

The Laser AF system works in the same way Sony’s Hologram AF works. It fires a scattered laser light across the scene, providing the contrast-detect AF system enough illumination to be able to lock on the subject. This means that the whole subject doesn’t need to be all illuminated in order for the Laser AF to be able to lock on it, only a little point of light is needed to make the job done. The result is a much improved AF system that can focus in low-light and even in completely dark situations.

Here’s a LG G3 Laser Focus tests done both in daylight and in almost completely dark room.

LG G3 Laser Auto Focus system versus a conventional AF system (without the Laser system) from LG exhibition.

So if I’m reading the map correctly, LG was able to improve this technology in terms of speed, and therefore make the laser AF system a preferred autofocusing system, which we might see in LG future smartphones.

Some people raised an important question, whether the laser AF system is safe. As with the Hologram AF, the system uses Class I low-power laser. Furthermore, this beam of light is split into several dots that are scattered across the scene, so it shouldn’t pose any safety issues. Of course the main limitation is that the lower-power laser is limited in range, and I expect somewhat the same range as with the Sony Hologram AF system, around 4.5 meters.

The Laser AF system will provide almost instantaneous distance detection of the subject if it’s within two feet  (~0.6 meters), and this time is increased when the subject is further away from the laser sensor.

I have no doubt that this new Laser Auto Focus will give the LG G3 an advantage when shooting in low-light, and together with an advanced optical image stabilizer (OIS+) and a fast aperture lens, will give the LG G3 a significant advantage in low-light versus the competition.

I will update this post with more information as more tests become available. Nevertheless, this technology looks very promising and I am eager to try it myself in practice.

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